A 6.9- $\mu$ m Pixel-Pitch Back-Illuminated Global Shutter CMOS Image Sensor With Pixel-Parallel 14-Bit Subthreshold ADC

In this paper, we report on a back-illuminated, global shutter, CMOS image sensor (CIS) with a pixel-parallel, single-slope analog-to-digital converter (ADC). We adopted a digital bucket relay transfer with multistage flip-flop connection, a pixel unit Cu-Cu connection, and positive-feedback circuitry, to realize a 6.9-μm pixel-pitch, 1.46-Mpixel pixel-parallel ADC. By operating the comparator wit...